Department of Public Health and Clinical Medicine, Sustainable Health, Umeå University, Sweden.
Department of Environmental Science - Atmospheric Modelling, Aarhus University, Denmark.
Environ Int. 2021 Oct;155:106667. doi: 10.1016/j.envint.2021.106667. Epub 2021 May 30.
Asthma is a complex, heterogeneous disease and one of the most common chronic diseases among children. Exposure to ambient air pollution in early life and childhood may influence asthma aetiology, but it is uncertain which specific components of air pollution and exposure windows are of importance. The role of socio-economic status (SES) is also unclear. The aims of the present study are, therefore, to investigate how various exposure windows of different pollutants affect risk-induced asthma in early life and to explore the possible effect SES has on that relationship.
The study population was constructed using register data on all singleton births in the greater Stockholm area between 2006 and 2013. Exposure to ambient black carbon (BC), fine particulate matter (PM), primary organic carbon (pOC) secondary organic aerosols (SOA), secondary inorganic aerosols, and oxidative potential at the residential address was modelled as mean values for the entire pregnancy period, the first year of life and the first three years of life. Swedish national registers were used to define the outcome: asthma diagnosis assessed at hospital during the first six years of life. Hazard ratios (HRs) and their 95% confidence intervals (CIs) were modelled with Cox proportional hazards model with age as the underlying time-scale, adjusting for relevant potential confounding variables.
An increased risk for developing childhood asthma was observed in association with exposure to PM, pOC and SOA during the first three years of life. With an interquartile range increase in exposure, the HRs were 1.06 (95% CI: 1.01-1.10), 1.05 (95% CI: 1.02-1.09) and 1.02 (95% CI: 1.00-1.04), for PM, pOC and SOA, respectively, in the fully adjusted models. Exposure during foetal life or the first year of life was not associated with asthma risk, and the other pollutants were not statistically significantly associated with increased risk. Furthermore, the increase in risk associated with PM and the components BC, pOC and SOA were stronger in areas with lower SES.
Our results suggest that exposure to air pollution during the first three years of life may increase the risk for asthma in early childhood. The findings further imply a possible increased vulnerability to air pollution-attributed asthma among low SES children.
哮喘是一种复杂的、异质性疾病，也是儿童中最常见的慢性疾病之一。在生命早期和儿童时期接触环境空气污染可能会影响哮喘的发病机制，但尚不确定空气污染的哪些特定成分和暴露窗口是重要的。社会经济地位（SES）的作用也不清楚。因此，本研究的目的是调查不同污染物的各种暴露窗口如何影响生命早期的风险诱导哮喘，并探讨 SES 对这种关系可能产生的影响。
该研究人群是使用 2006 年至 2013 年间大斯德哥尔摩地区所有单胎出生的登记数据构建的。在居住地址处，将环境黑碳（BC）、细颗粒物（PM）、初级有机碳（pOC）、二次有机气溶胶（SOA）、二次无机气溶胶和氧化势作为整个妊娠期间、生命第一年和生命前三年的平均值进行建模。使用瑞典国家登记册来定义结果：在生命的前六年期间在医院诊断出的哮喘。使用 Cox 比例风险模型，以年龄为基础时间尺度，对风险比（HRs）及其 95%置信区间（CIs）进行建模，调整了相关潜在混杂变量。
在生命的前三年暴露于 PM、pOC 和 SOA 与儿童哮喘发病风险增加有关。与暴露于 PM、pOC 和 SOA 的 IQR 增加相关，在完全调整模型中，HR 分别为 1.06（95%CI：1.01-1.10）、1.05（95%CI：1.02-1.09）和 1.02（95%CI：1.00-1.04）。胎儿期或生命第一年的暴露与哮喘风险无关，其他污染物与增加的风险无统计学意义相关。此外，在 SES 较低的地区，PM 以及 BC、pOC 和 SOA 等成分暴露增加的风险更高。
我们的研究结果表明，生命前三年暴露于空气污染可能会增加儿童早期哮喘的风险。研究结果进一步表明，低 SES 儿童可能更容易受到与空气污染相关的哮喘的影响。
